While both companies have memory chip plants in their home market, China accounts for a major slice of their global output.

The companies will now need to obtain licences to buy equipment for China, affecting sales and potentially aiding Chinese manufacturers.

The U.S. said Samsung and SK Hynix can no longer ship American equipment to their production facilities in China without government licenses.

While both companies have memory chip plants in their home market, China accounts for a major slice of their global output.